Disk drive system having a novel head actuator assembly and mounting plate configuration

ABSTRACT

The improved disk drive system has an improved head gimbal assembly having a mounting plate with an attachment portion for attachment to an actuator arm and a distal end for mounting the read/write heads, or load beam assemblies, thereto. The mounting portion and distal end of the mounting plate are vertically offset such that when the attachment portion is attached to the actuator arm, the distal end of the mounting plate is centered between opposing sides of adjacent disks, thereby permitting a smaller spacing between adjacent disks. The new swage type connection between the mounting plate and the actuator arm has a hole in the actuator arm and has a spud located on the attachment portion of the mounting plate. The spud has a cylinder having an outer diameter such that the cylinder can fit inside the actuator arm hole. A distal end of the cylinder has a lip protruding inwardly from an inside diameter of the cylinder. The cylinder has a length such that when the cylinder is inserted into the actuator arm hole, the lip and the distal end of the cylinder extend beyond the thickness of the actuator arm around the actuator arm hole so that when the spud is swaged while in the actuator arm hole, the lip and the distal end of the cylinder expand into an area outside the actuator arm hole.

This is a continuation of application Ser. No. 08/594,351, filed Jan.31, 1996 now abandoned, which is also a continuation of Ser. No.08/173,527, filed Dec. 23, 1993, now abandoned.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates in general to improvements in disk drivesystems and in particular to head gimbal assemblies for mountingread/write heads to an actuator hub, and to swage attachments forattaching head gimbal assemblies to actuator hubs.

2. Description of the Related Art

It has been a continuing objective of the disk drive industry to producedisk drive systems of increasing storage capacity, decreased size (or"form factor" as often used in the industry), and faster response time.One approach to increasing the storage capacity of a disk drive is toincrease the number of disks. However, as the number of disks increases,the height of the disk drive also increases. To maintain the desiredform factor of the disk drive, workers in the art are continually tryingto reduce the spacing between disks. However, the space between disksmust be sufficient to accommodate two read/write heads and two load beamassemblies on which the read/write heads are mounted.

While trying to reduce the spacing between disks, workers in the art arealso trying to reduce the mass of the actuator and head gimbal assemblyso as to decrease the response time of the disk drive. One way ofreducing the mass of the head gimbal assembly is to bring the actuatorhub closer to the center of the disk stack. This results in shorter, andthus lighter, head gimbal assemblies, and also in a disk drive having asmaller foot print.

One way to achieve the smallest possible spacing between the actuatorhub and the center of the disk stack is for the actuator arms to fitbetween the disks. Therefore, the space between disks must be sufficientto accommodate not only two read/write heads and two load beamassemblies on which the read/write heads are mounted, but also anactuator arm and the attachment means for attaching the head gimbalassembly to the arm.

FIG. 7 shows one type of prior art head gimbal assembly attached to anactuator hub. As is shown in FIG. 7, each load beam 130 is connected toan actuator arm 124 by a mounting member 128. Therefore, each actuatorarm 124, except for the upper and lower ones, has two load beams 130attached to it by means of two mounting members 128. This means thatbetween two disks 142 are located two load beams 130, one actuator arm124, and two mounting members 128. Having two mounting members 128, oneon each side of arm 124 adds considerably to the spacing requiredbetween disks.

Other prior art disk drives attempt to reduce the number of componentsbetween disks by attaching the load beams directly to the actuator arms,as, for example, by welding the load beams directly to the actuatorarms. However, with the spacing between disks, and hence the spacingbetween actuator arms getting smaller and smaller, it is becoming harderand harder to weld, or otherwise attach, the load beams directly to theactuator arms.

Certain prior art disk drives attempt to reduce the number of componentsbetween disks by attaching the load beams to the same side of theactuator arm, requiring only one attachment means and thus less verticalroom. However, this configuration is inadequate because the fixed endsof the two load beams are in contact with each other and thus allowundesirable vibrations to pass from one load beam to the other loadbeam.

Some prior art head gimbal assemblies, as explained above, are attachedto actuator arms by attaching the load beams directly to the actuatorarms. A different type of prior art head gimbal assemblies use amounting plate onto which the load beams are mounted. The load beams aremounted to the mounting plate before the mounting plate is attached tothe actuator arm. This makes attaching the load beams to the mountingplate easier since more room is available to make the attachment. Oncethe load beam assemblies are mounted onto the mounting plate, then themounting plate is attached to the actuator arm.

One method of attaching the head gimbal assemblies to the actuator armsis by means of swaging techniques. Prior art swaging techniques involvedswaging a spud, or boss, made of a hard material into an actuator armmade of a soft material. During prior art swage processes, a hard ballenlarges the spud cylinder, thus forcing the outside surface of the spudcylinder into the inside surface of the actuator arm hole, causing theoutside surface of the spud cylinder to "bite" into the inside surfaceof the actuator arm hole. However, with the spacing between disksgetting progressively smaller, the actuator arms must be made thinnerand thinner. In order for the actuator arms to have sufficient rigidityand strength they sometimes need to be constructed of harder materials.Although swage connections are well known in the art, if a hard materialis used for both the spud and the actuator arm, the current swagingtechniques will not work adequately since the hard spud will not easily"bite" into the hard actuator arm hole.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved disk drive assembly.

It is another object of the present invention to provide an improveddisk drive assembly having actuator arms that fit in between the disksof the disk stack.

It is another object of the present invention to provide an improveddisk drive assembly having a head gimbal assembly that permits closerdisk spacing.

It is another object of the present invention to provide an improveddisk drive assembly having a lighter head gimbal assembly to permit afaster response time.

It is another object of the present invention to provide an improveddisk drive assembly having a new swage attachment for attaching a hardmember to a hard actuator arm.

The foregoing objects are achieved as is now described. The improveddisk drive system has an improved head gimbal assembly having a mountingplate with an attachment portion for attachment to an actuator arm and adistal end for mounting the read/write heads, or load beam assemblies,thereto. The mounting portion and distal end of the mounting plate arevertically offset such that when the attachment portion is attached tothe actuator arm, the distal end of the mounting plate is centeredbetween opposing sides of adjacent disks, thereby permitting a smallerspacing between adjacent disks. The new swage-type connection betweenthe mounting plate and the actuator arm has a hole in the actuator armand a spud, or boss, located on the attachment portion of the mountingplate. The spud has a cylinder having an outer diameter such that thecylinder can fit inside the actuator arm hole. A distal end of thecylinder has a lip protruding inwardly from an inside diameter of thecylinder. The cylinder has a length such that when the cylinder isinserted into the actuator arm hole, the lip and the distal end of thecylinder extend beyond the thickness of the actuator arm around theactuator arm hole so that when the spud is swaged while in the actuatorarm hole, the lip and the distal end of the cylinder expand into an areaoutside the actuator arm hole.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further objectives and advantages thereof, willbest be understood by reference to the following detailed description ofan illustrative embodiment when read in conjunction with theaccompanying drawings, wherein:

FIG. 1 is an exploded view of a representative disk drive system.

FIG. 2 is a perspective view of an actuator hub and a head gimbalassembly of the present invention, showing only some of the actuatorarms for clarity.

FIG. 3 is a side view of the actuator hub and head gimbal assembly ofFIG. 2, showing all the actuator arms but not showing the wiring.

FIG. 4A is a side view of the mounting plate of FIG. 2.

FIG. 4B is a cross sectional view of the spud taken along line 4B inFIG. 3, and shown before the spud is swaged into the actuator arm hole.

FIG. 5 is a perspective view of an actuator hub and head gimbalassemblies of the present invention interacting with a disk stack.

FIG. 6 is a side view of the actuator hub, head gimbal assemblies, anddisk stack of FIG. 5.

FIG. 7 is a side view of prior art head gimbal assemblies attached to anactuator, showing only some wiring for clarity.

FIG. 8 is a perspective view of an alternative embodiment of themounting plate of the present invention, showing several mounting platesmounted to an actuator hub.

FIG. 9 is a perspective view of an embodiment of an actuator hub for usewith the new swage connection of the present invention.

FIG. 10 is a perspective cross sectional view of a mounting platelocated on an actuator arm, and showing the new spud attachment of thepresent invention before the spud is swaged; one cross section is takenhorizontally across the actuator, and the other cross section is takenvertically across the spud and actuator arm hole.

FIG. 11 is a perspective cross sectional view of a mounting platelocated on an actuator arm showing the new spud attachment of thepresent invention after the spud is swaged; one cross section is takenhorizontally across the actuator, and the other cross section is takenvertically across the spud and actuator arm hole.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

With reference now to the figures and in particular with reference toFIG. 1, there is depicted an exploded view of a representative diskdrive system or disk drive 10. It should be noted that although a rotaryactuator is shown, the invention described herein is applicable tolinear actuators. The disk drive 10 includes a housing 12, and a housingcover 14 which, after assembly, is mounted within a frame 16. Rotatablyattached within the housing 12 on an actuator shaft 18 is an actuatorassembly 20. One end of the actuator assembly 20 includes an E block oractuator hub 22 having a plurality of radially extending actuator arms24 (hidden from view in FIG. 1). Attached to the separate actuator arms24 of hub 22 are head gimbal assemblies 26. Each head gimbal assembly 26includes a mounting plate 28 attached to one of actuator arms 24.Attached to the end of mounting plate 28 are one or two load beams 30.Attached at the end of each load beam 30 is a slider 32 which carries apair of magnetic transducers or read/write head 34 (shown in FIG. 2). Onthe other end of the actuator assembly 20, opposite the load beams 30and the sliders 32, is a rotating means for rotating hub 22. Therotating means is shown as a voice coil 36 and magnets 38. Magnets 38are attached within housing 12. Magnets 38 and the voice coil 36 are thekey parts of a voice coil motor which applies a force to the actuatorassembly 20 to rotate it about the actuator shaft 18.

Also mounted within housing 12 is a spindle shaft 40. Rotatably attachedto spindle shaft 40 are a number of vertically spaced apart magneticdisks 42. An internal motor (not shown) rotates the disks 42. Disk drive10 also has circuitry to control the disk motor and the voice coil motorto allow selective positioning of the read/write heads over the disks.

FIG. 2 details part of the actuator assembly. In particular, it showshub 22 with a head gimbal assembly 26 attached thereto (only one headgimbal assembly 26, and only some actuator arms 24, are shown for betterclarity). FIG. 3 is a side view of the actuator assembly shown in FIG.2, and better shows some of the aspects of the present invention.Referring now mainly to FIGS. 2 and 3, head gimbal assembly 26 comprisesa mounting plate 28 for supporting two load beams 30. One load beam 30has a proximal end 50 attached to an upper face 52 of a distal end 54 ofmounting plate 28. The second load beam 30 has a proximal end 50attached to a lower face 58 of distal end 54 of mounting plate 28.Mounted to each load beam 30 is a slider 32 (only one slider 32 is shownin FIG. 2, the slider 32 on the lower load beam 30 is hidden from view).Each slider 32 supports a read/write head 34 attached to slider 32, andposition so as to read from and/or write to the corresponding disk 42.Load beams 30 are resiliently flexible in the vertical direction toallow slider 32 to follow the topography of disks 42, and are rigid inthe in-plane directions for precise slider positioning. Although notshown, a flexure is usually used to mount slider 32 to load beam 30.Also shown in FIG. 2, but not shown in FIG. 3, is wire 60 which runsfrom read/write heads 34, along the top of load beam 30, along the topand side of mounting plate 28, and to pad 77 where it connects to cable76. The short length of arm 24, and the use of mounting plate 28simplifies assembly since wire 60 can be routed and glued to head gimbalassembly 26 prior to attaching head gimbal assembly 26 to actuator arm24.

Referring now mainly to FIGS. 2, 3, 4A, and 4B, hub 22 has radiallyextending actuator arms 24. Mounting plate 28 of head gimbal assembly 26is attached to arm 24 by means of a swage connection. The swageconnection consists of an actuator arm hole 62 located in arm 24 and aspud, or boss, 64 (better shown in FIGS. 4A and 4B) protruding from anattachment portion 66 of mounting plate 28. Spud 64 has a cylinder 68sized such that it fits inside hole 62. Cylinder 68 is of a length suchthat the cylinder is fully contained inside hole 62 and does notprotrude beyond hole 62 when spud 64 is inserted into hole 62. Cylinder68 has a lip 70 protruding inwardly from an inside diameter of cylinder68. To make the swage connection, spud 64 is placed inside hole 62 andis then swaged by passing a hard ball through spud hole 72 of spud 64 toenlarge cylinder 68 thus causing the outside surface of cylinder 68 tobe forced outward and into the inside surface of hole 62. This causesspud 64 to "bite" into hole 62 thereby fixedly attaching mounting plate28, and hence head gimbal assembly 26, to actuator arm 24.

All the head gimbal assemblies are attached to the actuator arms in onestep. Head gimbal assemblies 26, already assembled and with wires 60already in place, are placed in their respective positions with spuds 64located inside actuator arm holes 62. Then, with all head gimbalassemblies 26 in place, a ball is passed through all the spuds in onepass, thereby attaching all head gimbal assemblies 26 to arms 24. Thisminimizes the amount of work that must be done in the restricted spacingbetween actuator arms 24 during attachment of head gimbal assemblies 26to arms 24.

Referring still mainly to FIGS. 2, 3, 4A, and 4B, an important featureof mounting plate 28 is depicted. Mounting plate 28 has a distal end 54and a proximal end 74. Attachment portion 66 is located at proximal end74. Attachment portion 66 and distal end 54 are vertically offset suchthat when mounting plate 28 is attached to arm 24 distal end 54 iscentered between opposing sides of adjacent disks 42. The exact amountof vertical offset depends on the thickness of arms 24 and on thespacing between disks 42. Preferably, the offset is of a magnitude thatresults in distal end 54 of mounting plate 28 being exactly centeredbetween two adjacent disks 42. However, certain applications mightrequire different offsets.

FIG. 5 shows actuator assembly 20 with hub 22 having eight arms 24 andeight head gimbal assemblies 26 attached thereto. Uppermost andlowermost head gimbal assemblies 26 only have one load beam 30 and oneslider 32 since only one disk surface needs to be read by these headgimbal assemblies 26. FIG. 6 shows a side view of the actuator assemblyshown in FIG. 5. Referring now mainly to FIGS. 5 and 6, the interactionbetween head gimbal assemblies 26 and disks 42 is shown. Arms 24 fitbetween disks 42 to allow closer spacing of hub 22 to the center ofdisks 42. Only one mounting plate 28 is attached to each arm 24.Attachment portions 66 of mounting plates 28 and distal ends 54 ofmounting plates 28 are offset vertically so that distal ends 54 arecentered between opposing sides of adjacent disks 42. The offset inmounting plates 28 provides additional room, as compared to the priorart, between the upper faces 52 of distal ends 54 of mounting plates 28and the adjacent surface of disk 42 so that additional room is createdfor accommodating upper load beams 30 and upper sliders 32, so thatdisks 42 can be spaced closer together. As shown in FIG. 6, offsetmounting plates 28 result in two sliders 32, and thus two read/writeheads 34, being mounted on one mounting plate 28. The use of offsetmounting plate 28 also results in only one actuator arm 24 and onemounting plate 28 being located between adjacent disks 42, therebydecreasing the amount of room needed between disks 42. The prior artdisk drives, on the other hand, as shown in FIG. 7, require two mountingmembers 128, in addition to an arm 124, between adjacent disks 142, thusrequiring more room between disks 142.

Another feature of the present invention is best shown in FIG. 2. Inorder to transfer information to and from read/write heads 34, wires 60must extend from pad 77 to read/write heads 34. With the thickness ofarms 24 and the spacing between arms 24 getting progressively smallerwith decreasing disk drive size, it is becoming increasingly difficultto route and glue wires 60 in the small space between arms 24 and alongthe very thin sides of arms 24. The present invention, by using shorterarms 24 and making up the difference in length with mounting plate 28,causes a greater portion of wires 60 to be located along head gimbalassembly 26. Routing and gluing wires 60 onto head gimbal assembly 26 iseasier than routing and gluing wires 60 onto arms 24, since on headgimbal assemblies 26, wires 60 can be routed and glued prior toattachment of head gimbal assemblies 26 onto arms 24. In contrast, theprior art, by using longer actuator arms 124 and by attaching load beams130 to actuator arms 124, resulted in a considerable length of wire 160being routed along the width of arm 124, or in between two arms 124 (asshown in FIG. 7). With the progressively decreasing arm thickness anddecreasing spacing between arms, routing wires 160 along arm 124 isbecoming increasingly difficult. The present invention offers a solutionto the problem since the wires are nearly completely along head gimbalassembly 26.

The mounting plate shown in FIGS. 2-6 is only one of many possibleembodiments of mounting plate 28. Mounting plate 28' shown in FIG. 8 isone of the many possible embodiments. Mounting plate 28' shown in FIG. 8has a distal end 54' and a proximal end 74' just like mounting plate 28of FIGS. 2-6. Mounting plate 28' also has an attachment portion 66' forattachment to arms 24' of hub 22'. Mounting plate 28' has an enlargedproximal end 74' to add stiffness and to provide additional room toguide wires 60'. The enlarged proximal end 74' that extends laterallybeyond arms 24' permits wires 60' to be routed completely on mountingplate 28 and avoids the need to route wires 60' along arm 24'. Theselection of the ideal mounting plate depends in large part on theparticular application and the particular parameters that need to beoptimized. The key feature of mounting plates 28 and 28' is the verticaloffset between attachment portions 66, 66' and distal ends 54, 54'.

Another embodiment of the present invention is shown in FIGS. 9-11. Theembodiment of FIGS. 9-11 is the preferred swage attachment for diskdrives that employ mounting plates and actuator arms that have similarhardnesses. In such disk drives, the conventional swage attachment usedin the embodiment of FIGS. 2-6 would be inadequate because a hard spudcannot easily "bite", or expand, into a hard actuator arm hole.Referring now mainly to FIG. 10, the new swage attachment is shownbefore spud 64" is swaged into actuator arm hole 62". The new swageattachment consists of an actuator arm hole 62" located in arm 24" andspud 64" protruding from an attachment portion 66" of mounting plate28". Arm 24" has a thickness 78" around actuator arm hole 62". Thethickness of the remainder of arm 24" can be the same as thickness 78",or it can be thicker, as shown in FIGS. 9-11, to add stiffness. Spud 64"has a cylinder 68" sized such that it fits inside hole 62". A distal endof cylinder 68" has a lip 70" protruding inwardly from an insidediameter of cylinder 68". Cylinder 68" is of a length such that when thespud is inserted into hole 62", the distal end of cylinder 68" extendsbeyond thickness 78" of arm 24". Spud 64" is swaged into hole 62" bypassing a hard ball through a spud hole 72" of spud 64". Referring nowalso to FIG. 11, when spud 64" is swaged, lip 70" and the distal end ofcylinder 68" expand into a free area outside the actuator arm holeinstead of expanding into the wall of actuator arm hole 62". As shown inFIG. 11, the expansion of lip 70' to an area outside hole 62' allows apositive attachment even if both the materials of mounting plate 28" andof arm 24" are hard.

While the invention has been particularly shown and described withreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

I claim:
 1. A disk drive system comprising:rotatably mounted, verticallyspaced apart magnetic disks, a disk motor for rotating said rotatablymounted, vertically spaced apart magnetic disks, an actuator hub, anactuator hub motor, a control circuit for controlling said disk motorand said actuator hub motor to allow selective positioning of read/writeheads over said rotatably mounted, vertically spaced apart magneticdisks; an actuator arm extending radially from said actuator hub, saidactuator arm having an attachment face and an unused face, said actuatorarm being attached to a double-head gimbal assembly; the double-headgimbal assembly having a mounting plate for attachment to said actuatorarm, a first load beam having a proximal end attached to a first face ofa distal end of said mounting plate, a second load beam having aproximal end attached to a second face of said distal end of saidmounting plate, a first slider mounted to said distal end of said firstload beam, a second slider mounted to said distal end of said secondload beam, a first read/write head attached to said first slider, asecond read/write head attached to said second slider; the mountingplate having a proximal end and a distal end, the proximal end beingadapted for connection to the actuator arm and the distal end beingadapted for connection to the first and second load beams; the mountingplate having an attachment portion at its proximal end for attachment tosaid attachment face of said actuator arm, and being attached to saidactuator arm by means of a swage-type attachment; the attachment portionof said mounting plate and the distal end of said mounting plate beingvertically offset wherein a smaller spacing between said opposingsurfaces of said adjacent, vertically spaced apart magnetic disks ispossible; an actuator arm hole located in said actuator arm; theactuator arm having a thickness around said actuator arm hole; a spudintegrally formed with said attachment portion of said mounting plate,said spud inserted into said actuator arm hole, said spud comprising acylinder, said cylinder having an initial outer diameter smaller than adiameter of said actuator arm hole, said cylinder being longer than saidthickness of said actuator arm; a lip on said distal end of saidcylinder; a recess formed in the actuator arm defining a free radialspace located outside said actuator arm hole and surrounding saidcylinder, said free radial space being free of any structure prior toswaging said lip so as to allow unimpeded expansion of said lip radiallyoutward, a portion of said free radial space being occupied by said lipafter said lip is swaged outwardly; said lip being swaged outwardly intosaid free radial space, thus resulting in said distal end of saidcylinder having a final outer diameter outside of said actuator arm holewhich is larger than said diameter of said actuator arm hole and thusattaching said mounting plate to said actuator arm; and said free radialspace being sufficiently large so that when said lip is swagedoutwardly, said lip occupies only a portion of said free radial space,thus leaving a radial void around said final outer diameter of saiddistal end of said cylinder after said lip is swaged outwardly.
 2. Aswage attachment for attaching a hard member to a hard actuator arm in adisk drive system, the swage attachment comprising:an actuator arm holelocated in said actuator arm; the actuator arm having a thickness aroundsaid actuator arm hole; the hard member having a proximal end and adistal end, the proximal end being adapted for connection to theactuator arm and the distal end being adapted for connection to a loadbeam; a spud integrally formed with an attachment portion at theproximal end of said hard member, said spud inserted into said actuatorarm hole, said spud comprising a cylinder, said cylinder having aninitial outer diameter smaller than a diameter of said actuator armhole, said cylinder being longer than said thickness of said actuatorarm; a lip on said distal end of said cylinder; a recess formed in theactuator arm defining a free radial space located outside said actuatorarm hole and surrounding said cylinder, said free radial space beingfree of any structure prior to swaging said lip so as to allow unimpededexpansion of said lip radially outward, a portion of said free radialspace being occupied by said lip after said lip is swaged outwardly;said lip being swaged outwardly into said free radial space, thusresulting in said distal end of said cylinder having a final outerdiameter outside of said actuator arm hole which is larger than saiddiameter of said actuator arm hole and thus attaching said hard memberto said actuator arm; and said free radial space being sufficientlylarge so that when said lip is swaged outwardly, said lip occupies onlya portion of said free radial space, thus leaving a radial void aroundsaid final outer diameter of said distal end of said cylinder after saidlip is swaged outwardly.
 3. The swage attachment according to claim 2wherein said thickness around said actuator arm hole is less than athickness of a remainder of said actuator arm.
 4. A disk drive systemcomprising:rotatably mounted, vertically spaced apart magnetic disks, adisk motor for rotating said rotatably mounted, vertically spaced apartmagnetic disks, an actuator hub, an actuator hub motor, a controlcircuit for controlling said disk motor and said actuator hub motor toallow selective positioning of read/write heads over said rotatablymounted, vertically spaced apart magnetic disks; an actuator armextending radially from said actuator hub; an actuator arm hole locatedin said actuator arm; the actuator arm having a thickness around saidactuator arm hole; a member having a proximal end and a distal end, theproximal end being adapted for connection to the actuator arm and thedistal end being adapted for connection to a load beam; a spudintegrally formed with an attachment portion on the proximal end of saidmember, said spud inserted into said actuator arm hole, said spudcomprising a cylinder, said cylinder having an initial outer diametersmaller than a diameter of said actuator arm hole, said cylinder beinglonger than said thickness of said actuator arm; a lip on said distalend of said cylinder; a recess formed in the actuator arm defining afree radial space located outside said actuator arm hole and surroundingsaid cylinder, said free radial space being free of any structure priorto swaging said lip so as to allow unimpeded expansion of said lipradially outward, a portion of said free radial space being occupied bysaid lip after said lip is swaged outwardly; said lip being swagedoutwardly into said free radial space, thus resulting in said distal endof said cylinder having a final outer diameter outside of said actuatorarm hole which is larger than said diameter of said actuator arm holeand thus attaching said member to said actuator arm; and said freeradial space being sufficiently large so that when said lip is swagedoutwardly, said lip occupies only a portion of said free radial space,thus leaving a radial void around said final outer diameter of saiddistal end of said cylinder after said lip is swaged outwardly.
 5. Adisk drive system according to claim 4 wherein said thickness aroundsaid actuator arm hole is less than a thickness of a remainder of saidactuator arm.